FYI, I opted to write my own version of the DBD::Oracle procedure so that I can successfully extract dbms_output lines up to the maximum length:

sub get_dbms_output {
   my $dbh = shift;
   my $sth = $dbh->prepare_cached('begin dbms_output.get_line(:line, :
+status); end;') or return;
   my ($line, $status, @lines);

   # Since 10g r2, Oracle has supported line sizes up to 32767.
   $sth->bind_param_inout(':line', \$line,  32767, { ora_type => 1 });
   $sth->bind_param_inout(':status', \$status, 20, { ora_type => 1 });
   if (!wantarray) {
       $sth->execute or return undef;
       return $line if $status eq '0';
       return undef;
   }
   push @lines, $line while($sth->execute && $status eq '0');
   return @lines;
}
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Once again, thanks for the quick and informed assistance!